1. Field of the Invention
This patent application relates to systems and methods for the directing and energy filtering of X-ray beams via diffraction and reflection using crystals (including Laue and Bragg diffraction). Embodiments in the field of non-intrusive inspection technology are presented. The capability to direct and energy filter X-ray beams greatly expands existing and potential applications of X-ray based inspection technologies.
The term X-ray is used to denote penetrating electromagnetic radiation and it is interchangeable with other traditional characterizations that use terms such as photons, gamma-rays, etc. when referring to electromagnetic radiation in the X-ray energy range.
2. Background Information
There are a variety of inspection regimes where the use of a directed or energy filtered X-ray beam may be highly advantageous.
A common method for producing a high intensity X-ray source in the photon energy range greater than 100 keV is electron bremsstrahlung. However, the bremsstrahlung process produces a continuous energy distribution of photons that are only weakly forward peaked for electron beam energies under consideration in non-intrusive inspection. The ability to direct this beam to a distant point may increase the distance over which inspections are practical by overcoming the divergence of the X-ray beam between the location of its production and the target, and the ability to energy filter may be advantageous in reducing the energy distribution of the incident photons.
Similarly, X-rays scattered from a target will fall off in intensity as the distance between the target and a detector is increased. A method of capturing these X-rays and imaging them onto a small detector may be very advantageous, in particular when the detectors require high photon energy-resolution and are very expensive. The result may be an increase in the distance over which such a system can operate, an increase in detection signal, reduced noise, and reduced cost.
There are coherent, nearly mono-energetic sources of X-rays in which the divergence and size of the beam is very small. These coherent sources of X-rays may be very useful for remote inspection since their size even at tens of meters may only be a few centimeters in diameter. However, the ability to inspect large objects (of order a meter or greater) may require some method to scan the beam over the target. An efficient mechanism for directing such a coherent nearly mono-energetic X-ray beam would be desirable.
Techniques for implementing inspection regimes are discussed in U.S. Pat. No. 5,115,459, Explosives Detection Using Resonance Fluorescence of Bremsstrahlung Radiation, U.S. Pat. No. 5,420,905, Detection of Explosives and Other Materials Using Resonance Fluorescence, Resonance Absorption, and Other Electromagnetic Processes with Bremsstrahlung Radiation, U.S. Pat. No. 7,120,226, Adaptive Scanning Of Materials Using Nuclear Resonance Fluorescence Imaging, U.S. Patent Publication No. 2006/0188060A1, Use of Nearly Monochromatic and Tunable Photon Sources with Nuclear Resonance Fluorescence in Non-intrusive Inspection of Containers for Material Detection and Imaging, U.S. Patent Publication No. 2007/0145973A1, Methods And Systems For Active Non-Intrusive Inspection And Verification Of Cargo And Goods, and U.S. Pat. No. 7,286,638, Methods and Systems for Determining the Average Atomic Number and Mass of Materials, the contents of each of which are incorporated herein by reference.